Stem cell properties of Gli1-positive cells in the periodontal ligament

Background: The periodontal ligament (PDL), which surrounds the tooth root, contains mesenchymal stem cells (MSCs) capable of differentiating into osteoblasts, cementoblasts, and fibroblasts under normal conditions. These MSCs are thought to have important roles in the repair and regeneration of injured periodontal tissues. However, since there is no useful marker for MSCs in the PDL, the characteristics and distributions of these cells remain unclear. Gli1, an essential hedgehog signaling transcription factor, functions in undifferentiated cells during embryogenesis. Previous studies have demonstrated that the dental epithelial and mesenchymal cells positive for Gli1 in developing teeth have stem cell properties, including the ability to form colonies and pluripotency. Therefore, the focus of this review is the stem cell properties of Gli1-positive cells in the PDL, with an emphasis on the differentiation ability of osteoblasts for the regeneration of periodontal tissues. Highlight: Lineage tracing analysis identified Gli1-positive PDL cells as MSCs that contribute to the formation of periodontal tissues and can regenerate alveolar bone. Conclusion: Gli1 is a potential stem cell marker in the PDL. A more definitive understanding of the functions of Gli1-positive cells could be useful for the development of regenerative methods using the MSCs in the PDL. (C) 2020 Japanese Association for Oral Biology. Published by Elsevier B.V. All rights reserved.